Why not?
by La Carta Esferica
Summary: Simon knew better than to listen when Jace suggested a fling as a way to get over a breakup. He really really did. (but he did it anyway)


**I'm back, and with an AU story about my OTP, I got suggested this idea on tumblr and here I am.**

**By the way, did anyone read CoHF? I can't even deal with the ending, I cried a lot!**

** And now, let's get on with the story!**

If Simon drank, he might have been drunk when Jace and Clary suggested it, and then he would actually have had an excuse for treating it like a valid suggestion. But he's sober, which makes it infinitely worse that he's heard "have a fling" so many times he's actually considering it as a way of getting over an ex.

Clary, though, is definitely pissed—she brought the booze, and she's drunk most of it, and now she's trying to comfort Simon, who has apparently been a right mess for the last two weeks, a claim of which Simon is intensely skeptical.

"Just find someone new to get with!" Jace says for the fourth or fifth or twentieth time, nearly yelling into Simon's ear even though the music isn't all that loud. "It's a laugh!"

Simon glares at him. It's a patently horrible idea, and every romantic comedy ever made knows it.

Behind the happy coupple who is rying to convince the poor boy, Alec and Magnus are having some sort of vicious slap fight punctuated by fits of giggling. Isabelle is nowhere to be fou—

Simon gets knocked forward into Clary by what turns out to be flying ball of inebriated Isabelle Lightwood, who may or may not want a piggyback ride. There's a smacking kiss to his check, but otherwise Isabelle ignores him completely in favor of Clary, asking if "our boy" is doing any better with his moping.

"Of course not," the read head says grandly. "He won't even kiss someone else!"

If Simon were going to kiss someone in an ill-advised attempt to get over—she who must not be named, yeah—it would probably be Isabelle, is the thing. Isabelle, who's awfully pretty and will kiss anyone who stands still long enough and not think anything of it, would be as good a choice as Simon can think of for a misguided one-off.

It's not going to happen, though.

Or rather, Simon tells himself that so frequently that he ends up spending a significant portion of the evening thinking about kissing her, and then wondering if Jace spiked his drink. They walk home together, Isabelle propped against Simon and asking repeatedly if she can stay at Simon's tonight. Simon caves on the grounds that Isabelle is pissed enough her mum won't be pleased, and Simon's mother is on a trip, so they stumble in, Izzy still draped all over Simon, and flop onto the sofa. He's more than a bit wired from the party, and he has exciting plans to make Isabelle drink a lot of water before she passes out, but they end up snuggled together, Iz giggling in his ear and Simon playing with her hair absently.

Isabelle is probably good at kissing, Simon thinks absently. She has a nice mouth, and she certainly does it a lot. Practice is good, right? And she'll get with anyone; Simon's seen her kissing Meliorn more more times than he has fingers, some friends she brought to Magnus parties a couple of times, and a lot of strangers. She had even joked about kissing Magnus and Clary.

Simon frowns, his fingers stilling against Izzy's head. Why hasn't she ever tried to kiss him? It's not even that Simon wouldn't have kissed her back—though he wouldn't have—but Isabelle's never made so much as a joking attempt to kiss him. It's not—right now, Izzy's face is pressed into the space where Simon's shoulder meets his neck and if it were anyone else, he's pretty sure they'd have been licked by now, but Izzy's not done anything except let her breath tickle Simon's skin. Her skin is warm, and she makes a soft, happy noise when Simon starts playing with her hair again, and it's suddenly even harder to stop thinking about what his blonde friend said, that kissing someone might help him.

Er, not that he needs help. He's perfectly happy. It's just that he does miss having someone to kiss—cuddling is nice and all, and his friends are more than happy to snuggle with him, but proper kissing is fun and it'd be pleasant enough to have someone to do it with. And Izzy's snuggled so close it's like she's trying to climb into Simon's lap, which is admittedly not outside the realm of possibility. She makes another tiny, slightly sleepy noise, pulls her face away from Simon's neck, and frowns. "I think I'm sobering up. Why am I sobering up?"

Izzy's frown is the cutest thing Simon's ever seen, and he wishes intensely that he'd had anything at all to drink so that he could pretend to justify that thought.

Simon kisses her.

There's a moment where Iz is clearly taken aback, frozen under Simon's lips, but she's trapped there by the hand Simon's still resting on her head—and then she's kissing back, lips pressed harder against Simon's, opening his mouth and licking into it. Distractedly, it occurs to Simon that he was right—Izzy is extremely good at this—but then he's caught up in the kissing, letting his fingernails trail lightly down Izzy's hips and swallowing the small whimper of a reaction he gets for it.

Something happens that Simon doesn't fully process because of Isabelle's mouth on his jaw, but all of a sudden he has a lap full of Isabelle Lightwood, whose hands are pushing his shirt up. Simon pulls her up into another kiss, biting at her lower lip and resting his hands on Izzy's hips. Somewhat reluctantly, he pulls away from Isabelle's lips—because honestly, maybe Jace was onto something with the suggestions of kissing, this is fantastic—but proves unable to stop himself pressing a messy line of kisses from Isabelle's ear down her neck. The sound Isabelle makes at that is as sleepy as it is—no, Simon's not going to let himself think the word "arousing" about a noise one of his best friends just made; that's so far from normal it doesn't bear thinking about.

Basically, she sounds sleepy, that's the important part. And she needs to have water before she goes to sleep, that's half the reason Simon is letting her stay over at all, to make sure she doesn't doom himself to a terrible hangover.

"Isabelle," he whispers. "I need to get up. Don't fall asleep before I get you a glass of water."

Pouting, Izzy squirms off Simon's lap and slumps over on the arm of the sofa. She's almost certainly going to be asleep before she drinks any water, and Simon's not sure it's worth the trouble of waking her up. Besides, she should have known better than to get so spectacularly drunk. And Simon is tired too.

He drags himself to the kitchen and back, leaving a glass of water on the coffee table in front of Isabelle, and curling up at the other end of the sofa. He does make a half-hearted attempt to cover them both with a blanket, but it lands mostly on the empty space between their feet, and Simon's asleep before he musters the energy to move it.

* * *

When he wakes up, it's to something poking him in the leg repeatedly—something that turns out to be Izzy. Simon has sprawled out a bit in sleep, his legs straightened so that his feet are almost in Isabelle's face, and she is getting him back by tapping out rhythmic patterns against his knee.

"How are you awake?" Simon grumbles, squinting into the morning sunlight that's filling the room.

Izzy grins broadly but doesn't answer. Frowning, Simon thinks of the previous night. "Why aren't you heinously hungover?"

"If I told you, I'd have to kill you," she answers, laughing. Simon rubs his eyes, because he needs a lot of energy to keep up with Isabelle at the best of times.

He pointedly doesn't mention the kissing. Isabelle almost certainly remembers it, because Simon knows how pissed she has to be to forget things and she'd been sobering up anyway but, well, it just seems like she ought to be the one mentioning it. Because of her having been slightly drunk and all.

Izzy carries on being terrifyingly perky, though, and doesn't bring up the kissing at all, or look at Simon a bit strange or look at his mouth or anything else. It's just—she also doesn't touch Simon at all, not after the poking to wake him up, and it's odd to the point of being disconcerting because Isabelle touches everyone, all the time, and with enthusiasm. They make some coffee—Isabelle makes coffee, Simon watches her vaguely and pretends he knows how to make any kind that isn't instant—and after Rebecca wakes up, she makes eggs and toast. It's a lovely morning except for how Simon didn't get nearly enough sleep, and Isabelle hasn't hit him once.

The fact that Simon is concerned about people not hitting him is the most depressing reflection of the state of his life basically ever.

After a couple hours of Simon pretending to do homework while Isabelle reads some magazines, he shoos her out because the pretending is all well and fun, but he does actually need to get his schoolwork done today, as Sundays are for voice lessons and practicing with the band, always have been. Izzy, predictably, pouts at him and complains that he works too hard and Simon tries not to let it bother him, the same way he's been trying not to let it bother him for as long as he's known Isabelle.

He has plenty of home this weekend, which is annoying but also a brilliant way to keep his mind off that thing where he kissed Isabelle kind of a lot and really not in a mates-goofing-off way. Simon's invited to Clary's on Sunday evening, as always, and accidentally spends most of the time he's there playing board games with Clary's family. When he goes to leave, Clary tails him out the door awkwardly and follows him down the street past a couple of houses.

"You alright?" she asks after a moment.

Simon nods, a little jerkily, and mutters "Fine."

Clary is—well, she's not Isabelle, but she's not that stupid, either. "You left early on Friday night."

"I needed to take Iz home, she was wasted." After that, Clary lets it drop and tells him to go home, but the conversation lingers in his mind as he walks home. There is, well, maybe he isn't doing as well as he thought he was. The only person he's seen since Saturday morning, other than his sister, is Clary and that's not really usual for them at all.

It's dark out by the time he gets back to his house, and he needs to get a head start on his reading for the week, or he would have kept walking to try and sort out what to do tomorrow.

* * *

In the end, Simon takes the easy way out and avoids talking to Isabelle as much as possible; it proves exceptionally easy because she is avoiding talking to him as well, or at least it seems that way. They sit as far apart as possible at lunch, and exchange only a few words about an assignment. Jace is very unsubtly watching them, and Simon can nearly see him working through what's happened since Friday night when Izzy was drunkenly jumping on Simon.

The thing is, it doesn't take Simon long to start missing Isabelle, which he didn't really anticipate in the slightest. They've always got on well enough, not as well as Clary and Simon or Alec and Jace or Magnus and every human on the planet, but Isabelle likes to be looked after and Simon likes to look after people, well, after her. And on top of that, they all just function as a unit, Izzy-and-Simon-and-Jace-and-Alec-and-Clary-and-Magnus, and they have for as long as Simon can remember, basically. Sometimes he spends too much time working and starts to miss them, but he's never actively avoided one of them before, never been deliberately spending less time with his best mates, and absolutely never had them not drag him away from his schoolwork when they miss him.

No one has been texting him at all hours, begging him to come out even though they know he can't (or rather, he doesn't think he ought to). Simon can't help wondering whether they know, whether Izzy told Clary and Clary told Jace and Alec and Alec told Magnus, or maybe if Izzy told Magnus and Magnus told the others, or maybe they all sat down at Starbucks together and Izzy told the story of how Simon snogged her on the sofa and it was odd because she'd never thought of Simon like that before.

It's a weird week—a lonely week, really—but Simon gets a lot of work done; by the end of it, he's ahead in his reading for all his subjects, has started all three of the essays he has due in the next few weeks, and has learned two new songs on the piano. Yeah, it's a bit strange that Jordan hasn't come by begging him to go out for burgers or Nando's, but he's always found that kind of annoying, and not having to put up with it isn't the worst thing that could happen. Jace has spent a lot less time trying to get Simon to bunk off school, too, which means Simon spends a lot less time explaining why it's important that he goes and works hard and pays attention.

Just—on balance, maybe it's not so bad, not having to be around the guys all the time.

Isabelle corners him in the loo at Louis's on Friday night; he's gone out cause it's Friday and he wants to see the lads, since they haven't been harassing him all week. "Si," she says, "it was just a bit of kissing between friends, yeah?"

Simon nods at her, jerky and too fast. Isabelle doesn't seem to notice, smiling wide and open. She darts in and presses a quick kiss to the corner of Simon's mouth then pulls back, looking at Simon so expectantly that he can't help leaning forward to kiss her again, just as quick. "So we're all good?" she says, and as soon as Simon has nodded a bit and squeaked out a yes, Isabelle is pressing him against the wall next to the towel rack and kissing him hard.

Closing his eyes, Simon forces himself not to think too hard, because this is just being casual and Izzy is friendly with everyone this way. He wraps an arm around Isabelle's waist instead, pulling her closer. It's surprisingly easy to just fall into kissing Iz, biting softly and hearing her gasp, feeling the drag of Izzy's teeth down his neck and gasping when she sucks hard against his collarbone.

Last time—the first time, maybe, maybe this is going to become a regular thing—it was sleepy and relaxed but now Isabelle is forceful, pinning Simon to the wall and kissing him in a mess of teeth and tongues that Simon finds himself returning enthusiastically. Isabelle kisses like she does most things, with too much energy and dragging everyone around her along.

When they slip back out of the loo, they don't even bother with a token effort at inconspicuousness because Simon has a love bite just above the neck of his t-shirt and Izzy's hair looks like it's had someone pulling at it—because Simon was. Clary catches Simon's eye and winks at him. "How was it?" she mouths, and Simon rolls his eyes but gives her a quick thumbs-up.

* * *

There is a possibility, however unlikely it seems to an outside observer, that not every single idea Jace-Herondale-Lightwood-whatever his last name was has is terrible and doomed to spectacular failure. It's a bit odd, making out with Isabelle, but it's not nearly as appalling a plan as Simon had feared.

Also, and this bears mentioning repeatedly and in extreme detail, he gets to kiss Izzy basically as much as he wants, and she is very good at kissing. At first, he can barely stop staring at Izzy's mouth all the time, which is conspicuous and unfortunate, but at least she seems to like it just as much. It's the polar opposite of the previous week, when Simon was so productive, because he spends every moment he's not sleeping or working kissing Isabelle.

It's definitely the best way he's found of not thinking about She Who Must Not Be Named—Clary made him pinkie promise he wouldn't use the bitch's name again and Simon is going to keep his promise, even though it's ridiculous. He owes Clary and her boyfriend that much, given the amount of time he's got to spend with his tongue in Izzy's mouth. Or on Izzy's neck. Or with Izzy's tongue on his collarbone.

There's more than one night that they waste sprawled across Isabelle's bed, putting up a half-hearted pretense that they're playing Mario Kart (or that Simon is playing Mario Kart and Isabelle is watching some magazines). It always devolves into making out quickly enough, when Simon goes for a celebratory kiss after winning and Iz tries to push him away while laughing, or Simon remembers that Isabelle's lips taste better than the controller he's been sucking on and pins her to the bed to kiss her thoroughly.

If it were possible to get used to the feeling of a squirming, happy lapful of Isabelle, Simon's sure he would have by now. Izzy's mum and dad go out a lot, and Simon spends most of those nights sitting on their sofa with Isabelle straddling his hips, pushing his hands under Isabelle's shirt and hauling her in as close as possible without breaking the kiss. They all blur together, hours spent kissing Izzy, until they don't anymore.

Simon bites at Izzy's lower lip—he's done it what feels like a thousand times before—but instead of her just letting out a gasp or a whimper, Izzy's hips rolled against his own. Simon's been trying not to think about this part, because it's weird to think about having sex with Izzy, because it's weird that he hasn't had sex with her yet. It feels kind of fucking spectacular, though; it feels like Simon's had a hard-on for the last ten minutes of kissing and this is the first relief he's had.

Isabelle knows he's hard too, which isn't really a surprise; Simon's got hard just about every time they've made out and he's sure Isabelle felt it, but they've never done anything except avoid looking at his crotch and all he did was hurry home to have a wank. This time, Izzy doesn't shy away, just grinds down onto Simon, who feels like his eyes are rolling back into his head. Since this—thing, whatever it is, since it started, he's been spending about as much time wanking as he has kissing Isabelle. But now, Izzy's pulling one of her hands out of Simon's hair and sliding it down his chest to fiddle with the button of his jeans. Simon groans quietly and pushes forward into it, and Izzy's eyes go extremely wide for a split second.

"Yeah?" she whispers, leaning forward to kiss Simon, whose answering "Yeah" is swallowed by Isabelle's mouth.

It's hard to stop, after that, because Simon knows how much better it is to kiss Izzy and actually have sex with that godess, or stick his hand into hers pants and make her scream until she can't take it anymore and starts twitching and gasping. Simon doesn't especially want to, either; this is even better than making out to keep his mind off anything else—he barely thinks about why this started it at all anymore.

* * *

A while—some indeterminate number of days that feels vaguely like a lot have passed—into the new arrangement where Simon gets to snog Izzy as much as he wants, Simon is wandering around Magnus' house in search of Isabelle. There's some sort of low-key party, no booze and a lot of video games, going on around him, but Simon's mostly interested in wasting a few minutes reminding himself about the gasp-like noise Isabelle makes when you string kisses along her jaw. If she's allowed to pull him into the corridor and kiss him breathless while his mother and sister are in the next room, he's allowed to drag her onto a sofa and do the same, regardless of who might see.

Izzy's dancing when Simon finally finds her; someone has found an ancient stereo and Izzy's twirling some poor boy around in an uncoordinated way that will probably kill them both. Just as Simon's about to call out to her, Izzy's head drops toward his shoulder and the tilt of her head is so familiar that Simon can't not see how she's kissing his shoulder, his neck, maybe biting his collarbone the way she does to Simon.

He's shaking a little as he bolts from the room and—that's not supposed to happen. It doesn't matter who else Isabelle kisses, because this is just a bit of snogging between friends. If Simon wanted to go and make out with Maia, that would be totally fine and he could go back to kissing Izzy later.

That's how flings work, right? Everyone gets laid and no one has to worry about their feelings getting hurt and it's just a bit of fun.

It really, really doesn't feel like just a bit of fun right now—if anything, this feels worse than the last breakup, because he wasn't anticipating it at all. He slumps, forehead resting against the wall so that no one will see if he gets a bit teary, and taps out a text to Clary:_ so tireddddd going home to crash :D._

Simon has been curled up on his bed for—he doesn't know how long, he can't see the clock with his face buried in the pillow when there's a sharp noise from his window. He ignores it, making a gesture he hopes conveys fuck off I'm having a cry, but it doesn't work, because a moment later Clary yells, "Let me in, you arsehole!" and Simon contemplates just leaving her there until the neighbors complain. Life would be easier if he were an arse, sometimes.

Scowling at Clary, he opens in the window and lets her in before faceplanting on his bed again. She settles down next to him, pressing her face against Simon's neck and wrapping an arm around his shoulders. "Did something happen with Izzy?" she asks.

Simon shakes his head, though he doubts that Clary felt that with the way he's smashed his face into the pillow. "I'm shit at flings," he says wetly, wishing that he didn't actually sound like he'd been crying into his pillow. Clary makes a strange noise that Simon can't identify, and pulls him in a bit closer, kissing his forehead quickly.

"Everyone's shit at flings, Lewis, haven't you ever seen a film?" Simonvsniggers a little through his tears.

"Izzy was kissing some boy," he mumbles, and Clary kisses him again, on the cheek this time, before shifting so that Simon has his face buried in Clary's shoulder.

Simon falls asleep that way, curled up against Clary, and when he wakes up, she is still there, snoring lightly into his neck. They eat breakfast together, Clary throwing bits of cereal at Simon when he's not expecting it and Simon trying to force the requisite smiles in reply. It's harder to keep up the pretense of happiness when Clary goes home, because even though he knows that he should be working, the temptation to just flop back across his bed is so strong. He can't get the picture of Isabelle with her face buried in the boy's neck out of his head—he's seen him before, thinks his name might be David, but it suddenly takes a lot of effort to remember how nice he is.

There is, well, there is a possibility he wasn't particularly good at the casual part of a lot of casual snogging and wanking with Isabelle, which gives him and overwhelming urge to punch Jace, Clary and also himself. This is exactly what he thought would happen and convinced himself wouldn't … and then it did.

* * *

By Sunday, he's ignored five calls from Izzy, and about three times as many texts (mostly from Izzy, but several from Jace as well). He went to the library on Saturday, because he never does that and it meant that he had a completely valid excuse for not answering his mobile. He's deep in the middle of sorting out the chords for a new song when there's an enthusiastic beating against his bedroom door that startles him out of it.

"Who is it?" he shouts, because his sister don't knock and his mother is out.

"It's Izzy," is the answer—she sounds a little nervous, maybe, or perhaps that's just Simon's own emotions.

"Go away!" he replies, which is kind of a long shot because Isabelle is what his friends call persistent and other people call "a pain in the arse."

"I wasn't kissing him!" she yells through the door, which is potentially the most mortifying thing that's ever happened to Simon, including the time that Jace pulled his trousers off and his pants came down with them. Well, actually it's less embarrassing than that, but only because it's just his sister around to hear.

Simon's off his bed in a split second, opening the door and dragging Isabelle into the room, then slamming it shut behind them. Izzy looks like she's trying very hard not to laugh, which Simon appreciates in the part of his brain that doesn't want to punch Jace, or cry.

"I really wasn't kissing David," Isabelle says, sitting down on the edge of Simon's bed awkwardly. He stays standing, unsure what to do with his hands, or the rest of his body, really.

"It's okay if you were," he says, which is not so much an answer as an entirely different conversation, but it's what came out of his mouth. And then the words process. "You weren't?"

Izzy shakes his head, and Simon feels like he needs to blink to make sure his eyes are clear. "But you were—and he—and we—"

This is going wonderfully. Izzy wasn't snogging David but that could mean that she hadn't got there yet when he found them, or that she didn't want to but he did want to be snogging Jace.

"I don't want to kiss anyone but you," Isabelle says, and then her eyes go wide. "Oh god, I, er, didn't mean to just say that like that. I-never mind." Her cheeks are as red as Simon's ever seen them and it—it's charming, and not in his normal Izzy-charm way. Simon kind of wants to kiss her, but he always wants anyway.

There's a silence, during which Simon is entirely too entranced by the way Isabelle bites her perfect lip, and then she adds, "If it was really just some kissing between friends, that's fine too. I won't do anything weird." She chews on her lip for a moment longer, and then continues. "At first I wanted it to be, but I don't know how and I didn't want it to be like that, I wanted to have something with you, and I was angry, and I was trying to forget it so I went to have fun with David, but when I though about kissing him I-I couldn't. I said we weren't a thing, that this was just a fling because I was scared that was all you wanted."

Simon can't help the laugh that bubbles out of him. "Didn't Clary tell you? I had a good cry on him after I thought I saw you kissing Dave." If Isabelle can blurt out emotions with no buildup, Simon can do it too. That's how this works, yeah?

Isabelle meets his eyes for the first time since he let slip that Simon is the only person she wants to kiss—which, oh god, Simon doesn't quite know what to do with that yet, his stomach feels like there are animals living in it—and looks hopeful.

"Do you—" Isabelle says, just as Simon starts with "Can I—"

They both giggle, though Simon knows his sounds a little hysterical. There's no way he's getting through this without a laughing breakdown or embarrassing himself so much he'll just have to jump out the window from shame. He just steps forward, standing between Isabelle's knees, and tilts Izzy's head up to kiss her..

Izzy makes a noise that's both familiar and completely new, a kind of relieved whimper that Simon swallows, unwilling to pull his lips off Izzy's. He's sinking to his knees, which proves difficult without breaking the kiss, but it's worth the struggle for the way he can thread his fingers into Isabelle's hair and pull her even closer. His other arm is wound tight around Isabelle's waist, fingers slipping under her shirt and tracing abstract patterns against her back.

When Izzy pulls back just slightly, nipping once at his jaw and then trailing sloppy kisses toward his ear, it occurs to Simon that he did forget to mention—"You're the only person I want to kiss, too."

He can actually feel Izzy's smile against his neck, the way her lips have gone tight and the edges of her teeth against the sensitive skin. Her hands travel down his chest and trace her abs, liie she wants to spend all her life doing that. Simon forgotes that in favor of dragging her back onto the bed and sealing their lips together again.

* * *

The next time Isabelle goes to kiss Simon when she's at Simon's for dinner, it's while his mother and sister are in the room. The experience is completely mortifying but makes Simon's heart do an extremely pleasant flopping thing, because that means this is definitely absolutely not just a bit of kissing. His family know and so do Isabelle's, and the two of them go to the cinema sometimes and don't pay any attention to the film-because to be honest, how can anyone pay attention to some kind of spectacle while by his side he had the most beautiful woman all around the world?

On top of all that, there's the way Isabelle won't stop touching Simon, even when it's really kind of a lot of work to keep it up, at school or when all six of them are piled together watching television. Not that Simon wants the touching to stop. (In fact, he would be pretty put out if it did.)

In the end, maybe Jace didn't have such a terrible idea after all.


End file.
